Where is my water tank?

If you think it's leaking from the tank, then the tank will be above where the leak is.

The tanks should be nearly exactly where the dump valves are. In my coach the freshwater tank sits at floor level with the black and grey tanks on top. My coach is not your coach but it might be a good place to start looking. There should be some removable wall panels allowing VERY limited access but you might be able to find the leaking connection (hopefully) once you get access.

It should have an overflow. Fill the tank until water runs from it; then it should be easy to find.

Our tank is just above the valve that says fresh water drain.

You need to find the exact place where the water is dripping from. Some fresh water tanks have a problem in that the overflow pipe will actually siphon water out of the tank and appear as a leak. My overflow pipe dripped water several feet away and on the opposite side of the water tank. Since I had a manual fill and vent above the tank on the wet compartment side, I just plugged the overflow several years ago to fix the problem.